#include<bits/stdc++.h>
using namespace std;
#define fs first
#define sc second
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define ALL(A) A.begin(),A.end()
#define RALL(A) A.rbegin(),A.rend()
typedef long long LL;
typedef pair<LL,LL> P;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<typename T> T gcd(T a,T b){return b?gcd(b,a%b):a;}
const LL mod=1000000007;
const LL LINF=1LL<<62;
const int INF=1<<30;
int dx[]={1,0,-1,0,1,-1,1,-1};
int dy[]={0,1,0,-1,1,-1,-1,1};
 

int main(){
    int q;cin >> q;
    while(q--){
        LL n,k;cin >> n >> k;
        if(k == 1){
            cout << n - 1 << endl;
            continue;
        }
        LL sum = 0;
        LL t = 1;
        int ans = 0;
        while(n > sum){
            sum += t;
            t *= k;
            ans++;
        }
        cout << ans - 1 << endl;
    }
    return 0;
}